The patterning of graphene is a powerful approach for tuning its physical and electronic structure and for controlling its integration into devices. Graphene patterned on the micron-scale has been employed to create ultrahigh frequency analog amplifiers, electrical interconnects, conduits for heat dissipation, and mechanical resonator membranes. At the nanometer-scale, the patterning of graphene modifies its electronic structure, opening up a band gap, thereby making it useful for semiconductor electronics and sensing. Nanostructured graphene materials are furthermore attractive for energy storage because of their ultrahigh surface area and the enhanced accessibility of the surfaces; and, nanoperforated graphene membranes with high pore density and flow conductance have been proposed as ideal ultrafiltration membranes.
A critical advantage of graphene, over other analogous, high-performance carbon materials such as nanotubes, is that its two-dimensional form factor naturally lends itself to patterning via scalable and standardized planar processing tools. Patterned graphene has typically been achieved by first exfoliating or growing graphene as a continuous membrane and then patterning it via subsequent top-down subtractive etching. A substantial disadvantage of top-down processing, however, is that it is limited in fidelity by the etching tools that are available, resulting in structural and chemical disorder that degrades graphene's exceptional properties, especially on the nanometer level.
The challenges presented by top-down processing have led to the exploration of superior bottom-up synthetic methods. However, bottom-up approaches have been limited by difficulties in controlling graphene growth orientation, assembly and pattern resolution.